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Shaban S, Patel M, Ahmad A. Antifungal activity of human antimicrobial peptides targeting apoptosis in Candida auris. J Med Microbiol 2024; 73. [PMID: 38743468 DOI: 10.1099/jmm.0.001835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024] Open
Abstract
Introduction. Innovative antifungal therapies are of crucial importance to combat the potentially life-threatening infections linked to the multidrug-resistant fungal pathogen Candida auris. Induction of regulated cell death, apoptosis, could provide an outline for future therapeutics. Human antimicrobial peptides (AMPs), well-known antifungal compounds, have shown the ability to induce apoptosis in pathogenic fungi.Hypothesis/Gap Statement . Although it is known that AMPs possess antifungal activity against C. auris, their ability to induce apoptosis requires further investigations.Aim. This study evaluated the effects of AMPs on the induction of apoptosis in C. auris.Methods. Human neutrophil peptide-1 (HNP-1), human β-Defensins-3 (hBD-3) and human salivary histatin 5 (His 5) were assessed against two clinical C. auris isolates. Apoptosis hallmarks were examined using FITC-Annexin V/PI double labelling assay and terminal deoxynucleotidyl transferase deoxynucleotidyl transferase nick-end labelling (TUNEL) to detect phosphatidylserine externalization and DNA fragmentation, respectively. Then, several intracellular triggers were studied using JC-10 staining, spectrophotometric assay and 2',7'-dichlorofluorescin diacetate staining to measure the mitochondrial membrane potential, cytochrome-c release and reactive oxygen species (ROS) production, respectively.Results and conclusion. FITC-Annexin V/PI staining and TUNEL analysis revealed that exposure of C. auris cells to HNP-1 and hBD-3 triggered both early and late apoptosis, while His 5 caused significant necrosis. Furthermore, HNP-1 and hBD-3 induced significant mitochondrial membrane depolarization, which resulted in substantial cytochrome c release. In contrast to His 5, which showed minimal mitochondrial depolarization and no cytochrome c release. At last, all peptides significantly increased ROS production, which is related to both types of cell death. Therefore, these peptides represent promising and effective antifungal agents for treating invasive infections caused by multidrug-resistant C. auris.
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Affiliation(s)
- Siham Shaban
- Department of Clinical Microbiology and Infectious Diseases, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2193, South Africa
| | - Mrudula Patel
- Department of Clinical Microbiology and Infectious Diseases, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2193, South Africa
- Division of Infection Control, Charlotte Maxeke Johannesburg Academic Hospital, National Health Laboratory Service, Johannesburg, South Africa
| | - Aijaz Ahmad
- Department of Clinical Microbiology and Infectious Diseases, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2193, South Africa
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
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Dzień E, Wątły J, Kola A, Mikołajczyk A, Miller A, Matera-Witkiewicz A, Valensin D, Rowińska-Żyrek M. Impact of metal coordination and pH on the antimicrobial activity of histatin 5 and the products of its hydrolysis. Dalton Trans 2024; 53:7561-7570. [PMID: 38606466 DOI: 10.1039/d4dt00565a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2024]
Abstract
This work focuses on the relationship between the coordination chemistry and antimicrobial activity of Zn(II) and Cu(II) complexes of histatin 5 and the products of its hydrolysis: its N-terminal fragment (histatin 5-8) and C-terminal fragment (histatin 8). Cu(II) coordinates in an albumin-like binding mode and Zn(II) binds to up to 3 His imidazoles. The antimicrobial activity of histatins and their metal complexes (i) strongly depends on pH - they are more active at pH 5.4 than at 7.4; (ii) the complexes and ligands alone are more effective in eradicating Gram-positive bacteria than the Gram-negative ones, and (iii) Zn(II) coordination is able to change the structure of the N-terminal region of histatin 5 (histatin 5-8) and moderately increase all of the studied histatins' antimicrobial potency.
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Affiliation(s)
- Emilia Dzień
- Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland.
| | - Joanna Wątły
- Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland.
| | - Arian Kola
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Via A. Moro 2, 53100 Siena, Italy
| | - Aleksandra Mikołajczyk
- Screening of Biological Activity Assays and Collection of Biological Material Laboratory, Wroclaw Medical University Biobank, Faculty of Pharmacy, Wroclaw Medical University, Borowska 211A, 50-556 Wrocław, Poland
| | - Adriana Miller
- Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland.
| | - Agnieszka Matera-Witkiewicz
- Screening of Biological Activity Assays and Collection of Biological Material Laboratory, Wroclaw Medical University Biobank, Faculty of Pharmacy, Wroclaw Medical University, Borowska 211A, 50-556 Wrocław, Poland
| | - Daniela Valensin
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Via A. Moro 2, 53100 Siena, Italy
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Perez-Rodriguez A, Eraso E, Quindós G, Mateo E. Antimicrobial Peptides with Anti-Candida Activity. Int J Mol Sci 2022; 23:ijms23169264. [PMID: 36012523 PMCID: PMC9409312 DOI: 10.3390/ijms23169264] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/10/2022] [Accepted: 08/13/2022] [Indexed: 02/06/2023] Open
Abstract
Mycoses are accountable for millions of infections yearly worldwide. Invasive candidiasis is the most usual, presenting a high morbidity and mortality. Candida albicans remains the prevalent etiologic agent, but the incidence of other species such as Candida parapsilosis, Candida glabrata and Candida auris keeps increasing. These pathogens frequently show a reduced susceptibility to commonly used antifungal drugs, including polyenes, triazoles and echinocandins, and the incidence of emerging multi-drug-resistant strains of these species continues to increase. Therefore, the need to search for new molecules that target these pathogenic species in a different manner is now more urgent than ever. Nature is an almost endless source of interesting new molecules that could meet this need. Among these molecules, antimicrobial peptides, present in different sources in nature, possess some advantages over conventional antifungal agents, even with their own drawbacks, and are considered as a promising pharmacological option against a wide range of microbial infections. In this review, we describe 20 antimicrobial peptides from different origins that possess an activity against Candida.
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Maksimov AY, Balandina SY, Topanov PA, Mashevskaya IV, Chaudhary S. Organic Antifungal Drugs and Targets of Their Action. Curr Top Med Chem 2021; 21:705-736. [PMID: 33423647 DOI: 10.2174/1568026621666210108122622] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 08/20/2020] [Accepted: 09/03/2020] [Indexed: 11/22/2022]
Abstract
In recent decades, there has been a significant increase in the number of fungal diseases. This is due to a wide spectrum of action, immunosuppressants and other group drugs. In terms of frequency, rapid spread and globality, fungal infections are approaching acute respiratory infections. Antimycotics are medicinal substances endorsed with fungicidal or fungistatic properties. For the treatment of fungal diseases, several groups of compounds are used that differ in their origin (natural or synthetic), molecular targets and mechanism of action, antifungal effect (fungicidal or fungistatic), indications for use (local or systemic infections), and methods of administration (parenteral, oral, outdoor). Several efforts have been made by various medicinal chemists around the world for the development of antifungal drugs with high efficacy with the least toxicity and maximum selectivity in the area of antifungal chemotherapy. The pharmacokinetic properties of the new antimycotics are also important: the ability to penetrate biological barriers, be absorbed and distributed in tissues and organs, get accumulated in tissues affected by micromycetes, undergo drug metabolism in the intestinal microflora and human organs, and in the kinetics of excretion from the body. There are several ways to search for new effective antimycotics: - Obtaining new derivatives of the already used classes of antimycotics with improved activity properties. - Screening of new chemical classes of synthetic antimycotic compounds. - Screening of natural compounds. - Identification of new unique molecular targets in the fungal cell. - Development of new compositions and dosage forms with effective delivery vehicles. The methods of informatics, bioinformatics, genomics and proteomics were extensively investigated for the development of new antimycotics. These techniques were employed in finding and identification of new molecular proteins in a fungal cell; in the determination of the selectivity of drugprotein interactions, evaluation of drug-drug interactions and synergism of drugs; determination of the structure-activity relationship (SAR) studies; determination of the molecular design of the most active, selective and safer drugs for the humans, animals and plants. In medical applications, the methods of information analysis and pharmacogenomics allow taking into account the individual phenotype of the patient, the level of expression of the targets of antifungal drugs when choosing antifungal agents and their dosage. This review article incorporates some of the most significant studies covering the basic structures and approaches for the synthesis of antifungal drugs and the directions for their further development.
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Affiliation(s)
- Alexander Yu Maksimov
- Department of Pharmacy and Pharmacology, Faculty of Chemistry, Perm State University, Perm 614990, Russian Federation
| | - Svetlana Yu Balandina
- Department of Pharmacy and Pharmacology, Faculty of Chemistry, Perm State University, Perm 614990, Russian Federation
| | - Pavel A Topanov
- Department of Pharmacy and Pharmacology, Faculty of Chemistry, Perm State University, Perm 614990, Russian Federation
| | - Irina V Mashevskaya
- Department of Pharmacy and Pharmacology, Faculty of Chemistry, Perm State University, Perm 614990, Russian Federation
| | - Sandeep Chaudhary
- Laboratory of Organic and Medicinal Chemistry (OMC lab), Department of Chemistry, Malaviya National Institute of Technology Jaipur, Jawaharlal Nehru Marg, Jaipur 302017, India
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Li X, Feng G, Wang W, Yi L, Deng L, Zeng K. Effects of Peptide C 12-OOWW-NH 2 on Transcriptome and Cell Wall of the Postharvest Fungal Pathogen Penicillium digitatum. Front Microbiol 2020; 11:574882. [PMID: 33042086 PMCID: PMC7527529 DOI: 10.3389/fmicb.2020.574882] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/24/2020] [Indexed: 11/17/2022] Open
Abstract
In this study, the transcriptional profiling of Penicillium digitatum after C12O3TR treatment was analyzed by RNA-Seq technology. A total of 2562 and 667 genes in P. digitatum were differentially expressed after 2 and 12 h treatment, respectively. These genes were respectively mapped to 91 and 79 KEGG pathways. The expression patterns of differentially expressed genes (DEGs) at 2 and 12 h were similar, mainly were the metabolic processes in cell wall, cell membrane, genetic information and energy. Particularly, the main metabolic process which was affected by C12O3TR stress for 2 and 12 h was cell integrity, including cell wall and cell membrane. The changes of chitin in cell wall was observed by Calcofluor White (CFW) staining assay. The weaker blue fluorescence in the cell wall septa, the decrease of β-1, 3-glucan synthase activity and the increase of chitinase and AKP activity showed that C12O3TR could damage the cell wall integrity. In conclusion, these results suggested that C12O3TR could inhibit the growth of P. digitatum through various mechanisms at transcriptional level, and could influence the cell wall permeability and integrity.
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Affiliation(s)
- Xindan Li
- College of Food Science, Southwest University, Chongqing, China
| | - Guirong Feng
- College of Food Science, Southwest University, Chongqing, China
| | - Wenjun Wang
- College of Food Science, Southwest University, Chongqing, China
| | - Lanhua Yi
- College of Food Science, Southwest University, Chongqing, China.,Research Center of Food Storage & Logistics, Southwest University, Chongqing, China
| | - Lili Deng
- College of Food Science, Southwest University, Chongqing, China.,Research Center of Food Storage & Logistics, Southwest University, Chongqing, China
| | - Kaifang Zeng
- College of Food Science, Southwest University, Chongqing, China.,Research Center of Food Storage & Logistics, Southwest University, Chongqing, China
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Xue YP, Kao MC, Lan CY. Novel mitochondrial complex I-inhibiting peptides restrain NADH dehydrogenase activity. Sci Rep 2019; 9:13694. [PMID: 31548559 PMCID: PMC6757105 DOI: 10.1038/s41598-019-50114-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 08/29/2019] [Indexed: 12/14/2022] Open
Abstract
The emergence of drug-resistant fungal pathogens is becoming increasingly serious due to overuse of antifungals. Antimicrobial peptides have potent activity against a broad spectrum of pathogens, including fungi, and are considered a potential new class of antifungals. In this study, we examined the activities of the newly designed peptides P-113Du and P-113Tri, together with their parental peptide P-113, against the human fungal pathogen Candida albicans. The results showed that these peptides inhibit mitochondrial complex I, specifically NADH dehydrogenase, of the electron transport chain. Moreover, P-113Du and P-113Tri also block alternative NADH dehydrogenases. Currently, most inhibitors of the mitochondrial complex I are small molecules or artificially-designed antibodies. Here, we demonstrated novel functions of antimicrobial peptides in inhibiting the mitochondrial complex I of C. albicans, providing insight in the development of new antifungal agents.
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Affiliation(s)
- Yao-Peng Xue
- Institute of Molecular and Cellular Biology, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan, ROC
| | - Mou-Chieh Kao
- Institute of Molecular Medicine, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan, ROC. .,Department of Life Science, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan, ROC.
| | - Chung-Yu Lan
- Institute of Molecular and Cellular Biology, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan, ROC. .,Department of Life Science, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan, ROC.
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The Synergistic Antibacterial Properties of Glycinin Basic Peptide against Bacteria via Membrane Damage and Inactivation of Enzymes. FOOD BIOPHYS 2019. [DOI: 10.1007/s11483-018-09564-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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8
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Antifungal Actions of Glycinin Basic Peptide against Aspergillus niger through the Collaborative Damage to Cell Membrane and Mitochondria. FOOD BIOPHYS 2018. [DOI: 10.1007/s11483-018-9561-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Łoboda D, Kozłowski H, Rowińska-Żyrek M. Antimicrobial peptide–metal ion interactions – a potential way of activity enhancement. NEW J CHEM 2018. [DOI: 10.1039/c7nj04709f] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We discuss the potential correlation between the antimicrobial peptide–metal binding mode, structure, thermodynamics and mode of action.
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Affiliation(s)
- D. Łoboda
- Faculty of Chemistry
- University of Wroclaw
- 50-383 Wroclaw
- Poland
| | - H. Kozłowski
- Public Higher Medical Professional School in Opole
- 45-060 Opole
- Poland
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Vieira MEB, Vasconcelos IM, Machado OLT, Gomes VM, Carvalho ADO. Isolation, characterization and mechanism of action of an antimicrobial peptide from Lecythis pisonis seeds with inhibitory activity against Candida albicans. Acta Biochim Biophys Sin (Shanghai) 2015; 47:716-29. [PMID: 26245301 DOI: 10.1093/abbs/gmv071] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 04/30/2015] [Indexed: 01/15/2023] Open
Abstract
Antimicrobial peptides (AMPs) are produced by a range of organisms as a first line of defense against invaders or competitors. Owing to their broad antimicrobial activity, AMPs have attracted attention as a potential source of chemotherapeutic drugs. The increasing prevalence of infections caused by Candida species as opportunistic pathogens in immunocompromised patients requires new drugs. Lecythis pisonis is a Lecythydaceae tree that grows in Brazil. The AMPs produced by this tree have not been described previously. We describe the isolation of 12 fractions enriched in peptides from L. pisonis seeds. Of the 12 fractions, at 10 μg/ml, the F4 fraction had the strongest growth inhibitory effect (53.7%) in Candida albicans, in addition to a loss of viability of 94.9%. The F4 fraction was separated into seven sub-fractions by reversed-phase chromatography. The F4.7' fraction had the strongest activity at 10 μg/ml, inhibiting C. albicans growth by 38.5% and a 69.3% loss of viability. The peptide in F4.7' was sequenced and was found to be similar to plant defensins. For this reason, the peptide was named L. pisonis defensin 1 (Lp-Def1). The mechanism of action that is responsible for C. albicans inhibition by Lp-Def1 includes a slight increase of reactive oxygen species induction and a significant loss of mitochondrial function. The results described here support the future development of plant defensins, specifically Lp-Def1, as new therapeutic substances against fungi, especially C. albicans.
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Affiliation(s)
- Maria Eliza Brambila Vieira
- Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013-602, Brazil
| | - Ilka Maria Vasconcelos
- Laboratório de Toxinas Vegetais, Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza, Brazil
| | - Olga Lima Tavares Machado
- Laboratório de Química e Função de Proteínas e Peptídeos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013-602, Brazil
| | - Valdirene Moreira Gomes
- Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013-602, Brazil
| | - André de Oliveira Carvalho
- Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013-602, Brazil
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How does it kill?: understanding the candidacidal mechanism of salivary histatin 5. EUKARYOTIC CELL 2014; 13:958-64. [PMID: 24951439 DOI: 10.1128/ec.00095-14] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Histatins are salivary cationic peptides that provide the first line of defense against oral candidiasis caused by Candida albicans. This minireview presents a critical evaluation of our knowledge of the candidacidal mechanism of histatin 5 (Hst 5). Hst 5 is the most potent among all histatin family members with regard to its antifungal activity. The mode of action of Hst 5 has been a subject of intense debate. Unlike other classical host innate immune proteins, pore formation or membrane lysis by Hst 5 has largely been disproven, and it is now known that all targets of Hst 5 are intracellular. Hst 5 binds C. albicans cell wall proteins (Ssa1/2) and glycans and is taken up by the cells through fungal polyamine transporters in an energy-dependent manner. Once inside the fungal cells, Hst 5 may affect mitochondrial functions and cause oxidative stress; however, the ultimate cause of cell death is by volume dysregulation and ion imbalance triggered by osmotic stress. Besides these diverse targets, a novel mechanism based on the metal binding abilities of Hst 5 is discussed. Finally, translational approaches for Hst 5, based on peptide design and synergy with other known drugs, are considered a step forward for bench-to-bed application of Hst 5.
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Houghton EA, Nicholas KM. In vitro reactive oxygen species production by histatins and copper(I,II). J Biol Inorg Chem 2008; 14:243-51. [DOI: 10.1007/s00775-008-0444-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Accepted: 10/09/2008] [Indexed: 12/15/2022]
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The antimicrobial peptide histatin-5 causes a spatially restricted disruption on the Candida albicans surface, allowing rapid entry of the peptide into the cytoplasm. PLoS Pathog 2008; 4:e1000190. [PMID: 18974864 PMCID: PMC2568956 DOI: 10.1371/journal.ppat.1000190] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Accepted: 09/26/2008] [Indexed: 11/19/2022] Open
Abstract
Antimicrobial peptides play an important role in host defense against microbial pathogens. Their high cationic charge and strong amphipathic structure allow them to bind to the anionic microbial cell membrane and disrupt the membrane bilayer by forming pores or channels. In contrast to the classical pore-forming peptides, studies on histatin-5 (Hst-5) have suggested that the peptide is transported into the cytoplasm of Candida albicans in a non-lytic manner, and cytoplasmic Hst-5 exerts its candicidal activities on various intracellular targets, consistent with its weak amphipathic structure. To understand how Hst-5 is internalized, we investigated the localization of FITC-conjugated Hst-5. We find that Hst-5 is internalized into the vacuole through receptor-mediated endocytosis at low extracellular Hst-5 concentrations, whereas under higher physiological concentrations, Hst-5 is translocated into the cytoplasm through a mechanism that requires a high cationic charge on Hst-5. At intermediate concentrations, two cell populations with distinct Hst-5 localizations were observed. By cell sorting, we show that cells with vacuolar localization of Hst-5 survived, while none of the cells with cytoplasmic Hst-5 formed colonies. Surprisingly, extracellular Hst-5, upon cell surface binding, induces a perturbation on the cell surface, as visualized by an immediate and rapid internalization of Hst-5 and propidium iodide or rhodamine B into the cytoplasm from the site using time-lapse microscopy, and a concurrent rapid expansion of the vacuole. Thus, the formation of a spatially restricted site in the plasma membrane causes the initial injury to C. albicans and offers a mechanism for its internalization into the cytoplasm. Our study suggests that, unlike classical channel-forming antimicrobial peptides, action of Hst-5 requires an energized membrane and causes localized disruptions on the plasma membrane of the yeast. This mechanism of cell membrane disruption may provide species-specific killing with minimal damage to microflora and the host and may be used by many other antimicrobial peptides.
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Isola R, Isola M, Conti G, Lantini MS, Riva A. Histatin-induced alterations in Candida albicans: a microscopic and submicroscopic comparison. Microsc Res Tech 2007; 70:607-16. [PMID: 17279506 DOI: 10.1002/jemt.20441] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Despite the numerous studies performed in an attempt to clarify the issue, the mechanism of action of salivary histatins remains unclear. The aim of the present study was to correlate histatin-induced morphological changes in Candida albicans by fluorescence microscopy (FM), transmission electron microscopy (TEM), and high resolution scanning electron microscopy (HRSEM). Each of the fluorescent dyes used by FM (i.e., tetramethylrhodamine methyl ester perchlorate for mitochondrial potential, Lysotracker for lysosome acidic compartment, and 4',6-diamino-2-phenylindole dihydrochloride for DNA) exhibited a specific staining in control cells. Following histatin treatment, we observed a recurring staining pattern, corresponding to fluorescence concentration along the cell periphery, suggesting a loss of dye specificity. To assess histatin-induced cytoplasmic modifications, ultrastructural analysis was then carried out. After treatments with histatins, TEM revealed characteristic intracellular modifications including: vacuole overgrowth, nuclear disappearance, loss of organelle identity, as well as the appearance of electron-dense membranes, likely of mitochondrial origin. Additionally, structures resembling autophagosomes were occasionally observed. By HRSEM, mitochondrial swelling was invariably the first sign of a histatin-induced effect. Other modifications included intracellular membrane disarrangement, organelles in disarray, and a large central cavity with deformed bodies displaced to the cell periphery, similar to what was detected by TEM. In summary, our study illustrates the occurrence of ultrastructural modifications following administration of histatins. Observations made with FM, TEM, and HRSEM provided different views of the same signs, demonstrating a definite action of histatins on C. albicans morphology. The possible functional meanings of these morphological results is discussed in light of the most recent biochemical data on histatin fungicidal activity.
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Affiliation(s)
- Raffaella Isola
- Department of Cytomorphology, University of Cagliari, Cittadella Universitaria di Monserrato, Monserrato (CA), Italy.
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Diaz G, Polonelli L, Conti S, Messana I, Cabras T, Putzolu M, Falchi AM, Fadda ME, Cosentino S, Isola R. Mitochondrial alterations and autofluorescent conversion ofCandida albicans induced by histatins. Microsc Res Tech 2005; 66:219-28. [PMID: 15940680 DOI: 10.1002/jemt.20161] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The mechanism of the candidacidal activity of histatins 3 and 5 (Hst) is still a matter of debate. Previous studies have indicated that Hst induce cell permeabilization, generation of reactive oxygen species (ROS) by mitochondria, inhibition of the respiratory chain, and energy-dependent cytotoxic release of ATP. On the other hand, the multiplicity of effects and the apparent contrast between experimental data continue to render the mechanism of Hst-induced killing of C. albicans unclear. In this investigation, using fluorescent probes (the potential-sensitive mitochondrial probe tetramethylrhodamine methyl ester perchlorate, TMRM; the ROS-sensitive probe dihydrofluorescein diacetate, DHF; the membrane-impermeant probe, calcein) and autofluorescence data we observed that Hst induce ROS generation by mitochondria undergoing a high energy swelling condition, accompanied by oxidation of cytosolic NAD(P)H and mitochondrial flavoproteins. ROS generation and swelling, attributable to an inhibition of the respiratory chain and to impairment of the K/H-exchanger, were followed by mitochondrial depolarization. Mitochondrial changes were accompanied by massive calcein influx, indicative of cell permeabilization, and prominent alterations of the cell size, shape, and optical density. The loss of proliferative activity was correlated, on a single cell basis, to the acquisition of a lipofuscin-like autofluorescence.
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Affiliation(s)
- Giacomo Diaz
- Dipartimenti di Citomorfologia, Università di Cagliari, 09042 Monserrato (Cagliari), Italy.
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